There is an ever increasing need to reduce the size, weight, cost and complexity of particle accelerators in applications beyond the usual high-energy physics, nuclear physics and synchrotron light sources where the accelerator designs have been largely based on the traditional large, complex, high-voltage, high-gradient designs. As the use of particle beams becomes more diversified and commonplace, the limitations inherent within prior legacy designs are becoming more evident. In the medical field, for example, the availability of accelerators that can be used for imaging or therapeutic purposes is limited by their size and cast, and operational characteristics, such as whether the accelerator is a cyclotron or a LINAC, power consumption (typically in the MW level) and cooling requirements (water cooling towers or liquid helium refrigerators). As such, these accelerators tend to be located in communities and facilities that can support these constraints, such as major accelerator complexes with access to high-voltage electrical equipment, high-volume water cooling systems and/or helium refrigeration, major hospitals or large irradiation facilities for food and mail sterilization. In particular, medical applications of accelerators have been predominantly on the use of electron accelerator for radiation cancer-treatment therapy, even though proton-beam therapy has been proven very efficacious in treating a variety of cancers. This is due to a $100M price tag for each proton accelerator (either a cyclotron or a synchrotron) and the proton beam delivering gantry system. As a result, only a handful of hospitals in the US offer their patients the proton beam therapy option. Unfortunately, the need for advanced care far exceeds the ability to provide it for those communities most in need. Most of the world's population does not reside near a hospital with particle beam therapy based on traditional accelerator designs, thus that population is denied the most advanced medical care available.
Aside from the delivery of advanced medical care, accelerators are used in energy and environmental research. For example, powerful x-ray beams produced by accelerators help scientists analyze protein structures, enabling them to develop new drugs designed to treat diseases such as cancer, diabetes, malaria, and even AIDS. In the areas of environmental safety and stewardship, blasts of electrons from an accelerator can effectively clean up dirty water, sewage sludge, and polluted gases from smokestacks. The same particles can be used to kill bacteria to prevent foodborne illnesses. Industry uses accelerator technology to implant ions in silicon chips. Such chips are used in many electronic products, such as computers, smart phones, and MP3 players. One final example of the utility of the field of the present invention is that particle accelerators can treat nuclear waste and enable the use of an alternative fuel, thorium, to produce green nuclear energy.
Advanced accelerator research is concerned with developing machines that can generate greater intensities, higher power, superior reliability, and enhanced efficiency. Concurrently, such accelerators must be designed so that they are more compact (smaller) and more cost-effective. Creating a more compact and cost-effective accelerator requires the ability to achieve high accelerating gradients in higher-frequency accelerating structures. The principal roadblock in such development is that at such high frequencies higher-order modes (parasitic, high-frequency oscillations of the accelerator structure) become excited by the very particle beam that propagates through the accelerating structure. These higher-order modes, or HOMs, interact with the accelerating beam, deteriorating its quality and intensity.
Accordingly, there is a need in the art for a compact and robust particle accelerator that can erase the structural and operational constraints on the design and delivery of high quality particle beams to be used in at least any of the aforementioned fields.